title: Bioconjugation of CdTe quantum dot for the detection of 2,4-dichlorophenoxyacetic acid by competitive fluoroimmunoassay based biosensor.
abstract: Quantum dots (QD) are semiconductor fluorescent nanoparticles, which can be made use of for environmental monitoring with high sensitivity. In view of the alarming levels of pesticides and herbicides being used in agriculture practices, there is a need for their rapid, sensitive and specific detection in food and environmental samples, as pesticides and herbicides are harmful to living beings even at trace levels. Present study was carried out to develop a reliable and rapid method for analysis and detection of 2,4-D (herbicide) using cadmium telluride quantum dot nanoparticle (CdTe QD). Fluoroimmunoassay based on the fluorescent property of quantum dot was used along with immunoassay to detect 2,4-D. CdTe capped with mercaptopropionic acid, was conjugated using N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and a coupling reagent like N-hydroxysuccinimide (NHS) to alkaline phosphatase (ALP) which was in turn conjugated to 2,4-D molecule. Anti 2,4-D-IgG antibodies were immobilized in an immunoreactor column using Sepharose CL-4B as an inert matrix. The detection of 2,4-D was carried out by fluoroimmunoassay-based biosensor using competitive binding between conjugated 2,4-D-ALP-CdTe and free 2,4-D with immobilized anti 2,4-D antibodies in an immunoreactor column. It was possible to detect 2,4-D upto 250pgmL(-1). Present study also emphasizes on the resonance energy transfer between ALP and CdTe QD as a result of bioconjugation, which can be used for future biosensor development based on quantum dot-biomolecular interactions.
authors.affiliation: Fermentation Technology and Bioengineering Department, Central Food Technological Research Institute, A Constituent Laboratory of Council of Scientific and Industrial Research, Mysore, Karnataka, India.
authors.forename: A C
authors.initials: AC
authors.lastname: Vinayaka
authors.forename: S
authors.initials: S
authors.lastname: Basheer
authors.forename: M S
authors.initials: MS
authors.lastname: Thakur
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000032:analysis* / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation*; D019187:Cadmium Compounds / Q000737:chemistry*; D004784:Environmental Monitoring / Q000295:instrumentation*; D004785:Environmental Pollutants / Q000032:analysis*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015200:Fluoroimmunoassay / Q000295:instrumentation* / Q000379:methods; D006540:Herbicides / Q000032:analysis / Q000737:chemistry; D045663:Quantum Dots; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D004785:Environmental Pollutants; D006540:Herbicides; D015084:2,4-Dichlorophenoxyacetic Acid; D013691:Tellurium; C028337:cadmium telluride